docs: def command_line(self):
          '''Return a string to open read files with'''
          file_format=self.guess_sequence_input_file_format(self.read_file)
          logging.debug("Detected file format %s" % file_format)
          if file_format == self.FORMAT_FASTA:
              cmd="""cat %s""" % (self.read_file)
          elif file_format == self.FORMAT_FASTQ_GZ:
              cmd="""zcat %s | awk '{print ">" substr($0,2);getline;print;getline;getline}' -""" % (self.read_file)
          elif file_format == self.FORMAT_FASTA_GZ:
              cmd="""zcat %s""" % (self.read_file)
          elif file_format == self.FORMAT_FASTQ:
              cmd="""awk '{print ">" substr($0,2);getline;print;getline;getline}' %s""" % (self.read_file)
          logging.debug("raw read unpacking command chunk: %s" % cmd)
          return cmd